After the '86 last year I had a river boat booked so cycled round and round until I found it (signposting was atrocious) and then waited round to leave, figuring that I could actually have comfortably just ridden to Greenwich where I was meeting the family (but I'd paid actual money for it, so was going to use it!).
Traffic at Hyde Park Corner was surprisingly free flowing, but traffic south of the river was a snarly nose to tail mess (I told you the river boat signposting was atrocious). It was quite odd suddenly being dumped in to heavy London traffic after hours of no cars or bothering with traffic lights during the event. So I guess it depends how patient she is with driving in and which direction you'd be looking to drive out.
Doing it again, I'd cycle straight to Greenwich (I think they had a closed road all the way back to Docklands you could use) and meet family there. So if I was travelling West I'd probably meet up in Kensington or somewhere slightly west of that. You can use your little sack thing that you leave with the lorries to carry the bits of the goodie bag you want to keep (a large number of people just dumped the lot to be honest). If you are being met, it doesn't take very long at all to get through the finish, maybe 15 minutes tops. I then did the chat on the phone for a bit thing, ate and drank something, then was feeling fresh enough to head off. After Wimbledon Hill, the spin in to the finish is great on the legs and left me comfortable to do another 10 (although the '86 did miss out two hills, swapping them for torrential rain). I think I ended up doing 98 miles all tolled for the day.
They had a tracking App which was OK, but was based on going over sensor strips so sometimes got confused. I ran the 'Glympse' App on my phone for the duration of the race which gave real time positioning. I'd recommend it (or something similar) if you can use it and are trying to meet up at the end as it'll give a lot more information on where you are when. Only downside with Glympse is it will only log 4 hours a go. You can add time, but you have to remember to give it some extra hours when you stop in the second half of the ride (well, I did anyway).
